The social and physical hazard associated with the use of marihuana is intimately related to its potential therapeutic benefit. It is therefore reasonable to examine the effect of the cannabinoids alone and in combination with other drugs which are misused and, which also, have therapeutic rationale. We therefore propose to extend our study of the toxicology of delta-9-tetrahydrocannabinol to include cannabinol and cannabindiol alone and also in combination with barbiturates (phenobarbital), ethanol, dextro amphetamine, morphine and certain anesthetic agents including halothine and nitrous oxide. The study of the effect on mental and motor performance in human subjects produced by smoking marihuana either alone or in conjunction with the taking of barbiturates, ethanol, dextro amphetamine and caffeine will continue. Our investigation will be expanded to include cannabinol and cannabidiol alone and in various combinations with delta-9-tetrahydrocannabinol mixed with placebo marihuana for smoking. Human studies involving anesthetic agents and pulmonary airway resistance and lung compliance are either contemplated or currently underway.